Olive Oil Constituents Quality Health Properties and Bioconversions Part 2 pot

Olive Oil – Constituents, Quality, Health Properties and Bioconversions 24 In a recent study, concerning the behaviour of super-intensive Spanish and Greek olive cultivars grown in northern Tunisia, Allalout et al. (2011) found significant differences between oils; they consider, the majority of the studied analytical parameters, to be deeply influenced by the cultivar-environment interaction. It seems there is an effect of genotype-environment interaction, responsible for olive oils characteristics. 4.3 Agronomic factors Irrigation, a practice that has been adequately studied, seems to produce a decrease in the oxidative stability of olive oil volatiles due to a simultaneous reduction in oleic acid and phenolic compounds contents (Tovar et al., 2002). According to Servili et al. (2007) the olive tree water status has a remarkable effect on the concentration of volatile compounds, such as the C 6 -saturated and unsaturated aldehydes, alcohols, and esters. Put simply, deficit irrigation of olive trees appears to be beneficial not only due to its well-known positive effects on water use efficiency, but also by optimizing olive oil volatile quality. Baccouri et al. (2008) reported an enhancement of the whole aroma concentration of Chetouil oils obtained from trees under irrigation conditions when compared to similar ones from non-irrigated trees. The effect of agronomic practices in oil quality is still controversial: data from Gutierrez et al. (1999) supports the hypothesis that organic olive oils have better intrinsic qualities than conventional ones. These olive oils usually present lower acidity and peroxide index, higher rancimat induction time, higher concentrations of tocopherols, polyphenols, o-diphenols and oleic acid. However, this work was carried out during 1 year, with one olive cultivar only, and results can not be generalized. Ninfali et al. (2008) in a 3-year study, comparing organic versus conventional practice did not observe any consistent effect on virgin olive oil quality. Genotype and year-to-year climate changes seem to have a proved influence. 4.4 Technogical factors Volatile compounds are predominantly generated during virgin olive oil extraction, and are important contributors to olive oil sensory quality. Virgin olive oil quality is intimately related to the characteristics and composition of the olive fruit at crushing. Changes in olive fruit quality during post-harvest is considered determinant to the final sensory quality. Kalua et al. (2008) reported that low-temperature storage of fruits can produce poor sensory quality of the final oil. This decrease in quality might be due to lower levels of E-hex-2-enal and hexanal, associated with a decrease in enzyme activity, and a concurrent increase in E- hex-2-enol, which might indicate a possible enzymatic reduction by alcohol dehydrogenase (Olias et al., 1993,Salas et al. 2000) and reduced chemical oxidation (Morales et al. 1997). Inarejos-Garcia et al. (2010) studied the olive oils from Cornicabra olives stored at different conditions (from monolayer up to 60 cm thicknesses at 10 ºC (20 days) and 20 ºC (15 days)). E-hex-2-enal showed a Gaussian-type curve trend during storage that can be related to the decrease of hydroperoxide lyase activity. C 6 alcohols showed different trends, during storage, with a strongly decrease of the initial content of Z-hex-3-en-1-ol after 15 and 8 storage days at 20ºC and 10ºC under the different storage layers, whilst an increase of E-hex- 2-en-1-ol was observed (except for mono-layer). Differences might be related to the Olive Oil Composition: Volatile Compounds 25 enhancement of alcohol dehydrogenase activity during storage. Besides the evolution and changes observed in the desirable LOX pathway, C 6 fraction, storage may give rise to undesirable volatile compounds, from metabolic action of yeasts, which was more evident when olive were stored at 20 ºC. The effect of the extraction process on olive oil quality is also well documented (Ranalli et al., 1996; Montedoro et al., 1992; Di Giovacchino, 1996; Koutsaftakis et al., 1999; Servili et al., 2004). Technological operations include several preliminary steps, leaf and soil removal, washing, followed by crushing malaxation and separation of the oil (and water) from the olive paste. This last step can be achieved by pressing (the oldest system), centrifugation (the most widespread continuous system), or percolation (based on the different surface tensions of the liquid phases in the paste). Ranalli et al. (2008) studied the effect of adding a natural enzyme extract (Bioliva) during processing of four Italian olive cultivars (Leccino, Caroleo, Dritta and Coratina) carried out with a percolation-centrifugation extraction system. The improved rheological characteristics of the treated olive paste resulted in a reduced extraction cycle with good effects concerning olive oil aroma characteristics. Results have shown that enzyme-treated olive pastes always release higher amounts of total pleasant volatiles (E-hex-2-enal, E-hex-2- en-1-ol, Z-hex-3-enyl acetate, Z-hex-3-en-1-ol, pent-1-en-3-one, Z-pent-2-enal, E-pent-2-enal and others). For the individual C 6 metabolites, from the LOX pathway, a similar trend was generally observed, while for the total unpleasant volatiles, n-octane, ethyl acetate, isobutyl alcohol, n-amyl alcohol, isoamyl alcohol and ethanol, an opposite behaviour was found. The fundamental step is, however, olive crushing. The release of oil from olives can be achieved by mechanical methods (granite millstones or metal crushers) or centrifugation systems. These different systems affect the characteristics of the pastes and the final oil (Di Giovacchino et al., 2002). Almirante et al. (2006) reported that the oils obtained from de-stoned pastes had a higher amount of C 5 and C 6 volatile compounds, when compared to oils obtained by stone-mills. This increment is due to stones removal, which possess enzymatic activities, metabolizing 13-hydroperoxides other than hydroperoxide lyase, giving rise to a net decrease in the content of C 6 unsaturated aldehydes during the olive oil extraction process. Servili et al. (2007) demonstrate that the enzymes involved in the LPO pathway have different activity in the pulp or in the stone. Stones seem to have a lower hydroperoxide lyase activity and a higher alcohol dehydrogenase activity when compared to the pulp. These authors also found higher amounts of C 6 unsaturated aldehydes olive oils volatiles (VOOs) obtained with the stoning process; the stone presence in traditional extraction procedure increases the concentration of C 6 alcohols (for Coratina and Frantoio cultivars). The next step is the malaxation. Malaxation is performed to maximize the amount of oil that is extracted from the paste, by breaking up the oil/water emulsion and forming larger oil droplets. The efficiency of this operation depends upon time and temperature. Pressing, percolation, or centrifugation, are finally used to separate the liquid and solid phases. Temperature and time of exposure of olive pastes to air contact (TEOPAC), during malaxation, affect volatile and phenolic composition of virgin olive oil, and consequently its sensory and healthy qualities. Cultivar still plays a fundamental role for the final composition (Servili et al, 2003). These authors showed that TEOPAC can be used to perform a selective control of deleterious enzymes, such as polyphenol oxidase (PPO) and Olive Oil – Constituents, Quality, Health Properties and Bioconversions 26 peroxidase (POD), preserving the activity of LPO. High malaxation temperature (> 25 ºC) reduces the activity of enzymes, involved in LOP pathway, reducing the formation of C 6 saturated and unsaturated aldehydes. A similar result is described by Tura et al. (2004). These authors found that changes in malaxation time and temperature produces differences in the volatile profile of olive oils. Increasing temperature and decreasing time led to a reduction in the amount of volatiles produced, but they also describe cultivar as the single most important factor in determining volatile profile of olive oils. The decrease of olive oil flavour, produced by high malaxation temperature, is due to the inactivation of hidroperoxide lyase (HPL) rather than lipoxygenase (LOX), as both enzymes have different behaviour regarding temperature (Salas & Sánchez, 1999b). LOX, when assayed with linoleic acid as the substrate, displayed a rather broad optimum temperature around 25 ºC and maintained a high activity at temperatures as high as 35 ºC, but HPL activity peaked at 15 ºC and showed a clear decrease at 35 ºC, in assays using 13-hydroperoxylinoleic acid as substrate. Similar results were obtained by Gomez-Rico et al. (2009) who observed a significant increase in C 6 aldehydes, in the final oil, as malaxation time increased; almost no changes in the content of C 6 alcohols were observed. Opposite results were found for the influence of the kneading temperature, where a drop in the C 6 aldehydes content as malaxation temperature increases is observed, especially for E-hex-2-enal and a slight increase in C 6 alcohols, mainly hexan-1-ol and Z-hex-3-en-1-ol. The final step of olive oil production also affects olive oil quality. Separation of oil from water can be achieved using a two-phase or a three phase centrifugation system. Comparing monovarietal virgin oils obtained by both processes, the oils from two-phase decanters have higher content of E-hex-2-enal and total aroma substances but lower values of aliphatic and triterpenic alcohols (Ranalli & Angerosa, 1996). Masella et al. (2009), when studying the influence of vertical centrifugation on olive oil quality, observed significant differences both in the total volatile concentration and in the two volatile classes from the LOX pathway involving LnA conversion. The observed decreased of C 6 /LnA and C 5 /LnA compounds can be explained by the volatiles partition between oil and water phases during vertical centrifugation. Storage conditions also affect final quality. Light exposure, temperature and oxygen concentration, storage time and container materials are also determinant. A study by Stefanoudaki et al. (2010) evaluating storage under extreme conditions, showed subtle differences, in the pattern of volatile compounds, in bottled olive oils stored indoors or outdoors. When stored with air exposure the levels of some negative sensory components, such as penten-3-ol and hexanal, increased while other positives, like E-hex-2-enal were reduced. Filling the headspace with an inert gas can reduce spoilage. 5. Analytical methodologies for quantitation and identification of volatiles compounds: New analytical methods 5.1 Olive oil volatile compounds In the volatile fraction of olive oils, approximately three hundred compounds have already been detected and identified by means of gas chromatography/mass spectrometry (GC/MS) methods (Boskou, 2006). Among these compounds, only a small fraction Olive Oil Composition: Volatile Compounds 27 contributes to the aroma of olive oil (Angerosa et al., 2004). The most common olive oil volatiles have 5 to 20 carbon atoms and include short-chain alcohols, aldehydes, esters, ketones, phenols, lactones, terpenoids and some furan derivatives (Reiners & Grosh, 1998; Delarue & Giampaoli, 2000; Kiritsakis, 1992; Boskou, 2006; Vichi et al., 2003a, 2003b, 2003c; Aparicio et al., 1996; Morales et al., 1994; Flath et al, 1973; Morales et al, 1995; Bortolomeazzi et al., 2001; Bentivenga et al., 2002; Bocci et al., 1992; Servili et al., 1995; Fedeli et al., 1973; Fedeli, 1977; Jiménez et al., 1978; Kao et al., 1998; Guth & Grosch, 1991). As all vegetable oils, olive oil comprises a saponifiable and a non-saponifiable fraction and both contribute for the aroma impact. As a result of oxidative degradation of surface lipids (Reddy & Guerrero, 2004) a blend of saturated and mono-unsaturated six-carbon aldehydes, alcohols, and their esters (Reddy & Guerrero, 2004; Matsui, 2006) are produced. As already mentioned they are formed from linolenic and linoleic acids through the LOX pathway, and are commonly emitted due to defence mechanism developed by the plant in order to survive to mechanical damage, extreme temperature conditions, presence of pathogenic agents, among others (Delarue & Giampaoli, 2000; Noordermeer et al., 2001; Pérez et al., 2003; Angerosa et al., 2000; Angerosa et al., 1998b). Volatile phenols are also reported as aroma contributors for olive oil and can play a significant organoleptical role (Vichi et al., 2008; Kalua et al., 2005). 5.2 Analytical methodologies 5.2.1 Sample preparation procedures When the analysis of a volatile fraction, of complex matrices, is considered sample preparation cannot be underestimated. In biological samples, a wide chemical diversity, in a wide range of concentrations, must be expected (Salas et al., 2005; Wilkes et al., 2000). The chemical nature, and the amount of the detected compounds, strongly depends on the extraction technique used, to remove and isolate them from their matrices. The choice of a suitable extraction methodology depends on sample original composition and target compounds. However, an ideal sampling method does not exist and no single isolation technique produces an extract that replicates the original sample. In order to have enough quantity of each compound to be detected by chromatography, a concentration step must, usually, be considered. Sample preparation can be responsible for the appearance of artefacts, due to the chemical nature of the compounds extracted, and thus detected and quantified, and to a total or partial loss of compounds; this issues can, very strongly, determine the precision, reproducibility, time and cost of a result and/or analysis (Wilkes et al., 2000; Belitz et al., 2004; Buttery 1988; van Willige et al., 2000). These methods are revised in a recent manuscript (Costa Freitas et al.) where sample preparation procedures for volatile compounds are discussed as well as the advantages and drawbacks of each method. In olive oil analysis, its oily nature strongly influences the choice of the extraction procedure. There are various techniques that can be used for the preparation of the sample analytes in biological material. From those so far applied, liquid extraction with or without the use of ultrasounds (Kok et al., 1987; Fernandes et al., 2003; Cocito et al., 1995) is probably the most used. Besides liquid extraction, simultaneous distillation extraction (SDE) (Flath et al., 1973) has also been widely used. The drawback of these methods is the use of solvents Olive Oil – Constituents, Quality, Health Properties and Bioconversions 28 and consequently the need of compounds isolation from the solvent which represents an extra preparation step, as well as the dilutions steps during the extraction procedure. To avoid these steps, supercritical fluid extraction (SFE) (Morales et al., 1998) was also used for the isolation of volatile constituents of olive oil. The methods based on extraction from the headspace are an elegant choice (Swinnerton et al., 1962). The more often used procedures are the so called “purge and trap” techniques (Morales et al., 1998; Servili et al., 1995; Aparicio & Morales, 1994) in which the compounds of interest are trapped in a suitable adsorbent, from which they can be taken either directly (using a special “thermal desorber” injector) or after retro-extraction into a suitable solvent which, once again, includes an extra extraction step. Another choice is direct injection of the headspace into the injection port of a GC chromatograph. This possibility does not include a concentration step, and consequently, the minor compounds are usually missing or not detected (Del Barrio et al., 1983; Gasparoli et al., 1986). A direct thermal desorption technique can also be applied, avoiding the use of any types of adsorbents, by just heating the target olive oil sample to a suitable temperature in order to promote the simultaneous, extraction, isolation and injection of the volatile fraction into the analytical column (Zunin et al. 2004, de Koning et al., 2008). The main advantage of this technique is its simplicity, although a special injection system is mandatory, which can be expensive. When SPME was introduced (Belardi & Pawliszyn, 1989; Arthur & Pawliszyn, 1990) several authors have focused their attention on adapting the technique for aroma compounds analysis (D’Auria et al., 2004; Vichi et al., 2003; Vichi et al., 2005; Ribeiro et al., 2008). The main advantages of this technique are: a) it does not involve sample manipulations; b) it is an easy and clean extraction method able to include, in just one step, all the steps usually needed for aroma extraction. The extraction step, in SPME, can be made either by headspace sampling or liquid sampling. Headspace sampling (HS) is usually the method of choice for olive oil aroma analysis. The fibre chemical composition is of main interest and determines the chemical nature of the compounds extracted and further analyzed. There are several coatings commercially available. Polydimethylsiloxane (PDMS) and polyacrylate (PA) coatings extract the compounds by means of an absorption mechanism (Ribeiro et al., 2008) whereas PDMS is a more apolar coating then PA. Polydimethylsiloxane/divinylbenzene (PDMS/DVB), polydimethylsiloxane/carboxene (PDMS/CAR), carbowax/divinylbenzene (CW/DVB), and divinylbenzene/carboxene/polydimethylsiloxane (DVB/CAR/PDMS) extract by an adsorptive mechanism. These second group of fibres have usually a lower mechanic stability but present higher efficiency to extract compounds with low molecular weight (Augusto et al., 2001). In both extraction mechanisms, once the compounds are expelled form the matrix, they will remain in the headspace and a thermodynamic equilibrium is established between these two phases (Zhang & Pawliszyn, 1993). When the fibre is introduced a third phase is present and mass transfer will take place in both interphases (sample matrix/headspace and headspace/fibre). When quantification is a requirement, equilibrium has usually to be achieved. Time and temperature are also very important issues to take in consideration, since they will affect equilibrium (Vas & Vékey, 2004) and thus extraction efficiency. Methods that consider quantification in non- equilibrium have also been developed (Ai, 1997; Ribeiro et al., 2008). In order to optimize the extraction procedures by HS-SPME, the efficiency, accuracy and precision of the extraction is also directly dependent on operational parameters like extraction time, sample agitation, pH adjustment, salting out, sample and/or headspace volume, Olive Oil Composition: Volatile Compounds 29 temperature of operation, adsorption on container walls and desorption conditions (Pawliszyn, 1997). 5.2.2 Chromatographic methods for the analysis of olive oil volatiles Capillary gas chromatography (GC) is the most used technique for the separation and analysis of volatile and semivolatile organic compounds (Beesley et al., 2001) in biological samples. GC allows to separate and detect compounds present in a wide range of concentrations in very complex samples, and can be used as a routine basis for qualitative and quantitative analysis (Beesley et al., 2001; Majors, 2003). Enantioselective separations can also be performed when chiral columns are used (Bicchi et al., 1999). The most common detector used is the flame ionization detector (FID), known by its sensitivity and wide linear dynamic range (Scott, 1996; Braithwaite & Smith, 1999). When coupled with Fourier transform infrared spectroscopy (GC/FTIR) or mass spectrometry (GC/MS) (Gomes da Silva & Chaves das Neves, 1997; Gomes da Silva & Chaves das Neves, 1999 ), compounds tentative identification can be achieved. The most widely used ionization techniques employed in GC/MS is electron ionization (EI normally at 70 eV) and the more frequently used mass analysers, in olive oil volatile research, are quadrupole filters (qMS), ion traps (ITD) and time of flight instruments (TOFMS). The GC/TOFMS instruments allow the simultaneous acquisition of complete spectra with a constant mass spectral m/z profile for the whole chromatographic peak, while in qMS instruments the skewing effect is unavoidable. This fact enables the application of spectral deconvolution (Smith, 2004), and, potentially, a more accurate use of reference libraries for identification and confirmation of analytes may be possible. Nevertheless, for routine laboratory the development of TOFMS dedicated mass spectral libraries, to complement the libraries now generated by using qMS, should be considered. Spectral matching is usually better when qMS data are compared in some instances (Cardeal et al., 2006; Gomes da Silva et al., 2008). In an ongoing research in our lab, HS-SPME was performed in order to identify volatile compounds in Galega Vulgar variety. Four fibres were used and the HS-SPME-GC/TOFMS system operated with a DB-wax column. In table 1 the complete list of compounds identified (using the four different fibres) is provided as well as fragmentation patterns obtained for those not yet reported in olive oils (table 2). Analysis were performed in two columns: a polar column (DB-WAX), usually recommended for volatiles analysis, and an apolar based column DB-5. The use of these two columns, of different polarity, was also very useful to detect co-elutions, occuring when the polar column was used, and helped the identification task, when associated to mass spectrometric and linear retention indices (LRI) data confrontation. Most identification were performed by comparing retention time and fragmentations patterns, obtained for standards, analysed under the same conditions, or by fragmentation studies, when standards were not available. The differences observed, in the LRI experimentally obtained for the DB-WAX column, compared to the literature were expectable since polar columns are known as being much more unstable, then apolar columns, and cross-over phenomena occur (Mateus et al. 2010). Their retention characteristics varies significantly among different suppliers, which suggest the need of LRI probability regions. This fact explains why few LRI data is available for polar columns. These results aims to fullfill some part of this gap. Olive Oil – Constituents, Quality, Health Properties and Bioconversions 30 Compound name LRI Experimental [Literature] SPME Fibres Compound name LRI Experimental [Literature] SPME Fibres Hexane n.d. [600] D-C-P E-Pent-2-enal 1060 [1127-1131] D-C-P Heptane n.d. [700] PA D-C-P p-Xilene 1067 [1133-1147] PA D-C-P Octane 800 [800] PA D-C-P Butan-1-ol 1074 [1147] PA D-C-P Propanone 808 [820] PA CDVB D-C-P m-Xilene 1077 [1133-1147] D-C-P E-Oct-2-ene 818 [n.f.] PA Pent-1-en-3-ol 1093 [1130-1157] PA D-C-P Ethyl acetate 832 [892] D-C-P 2,6-Dimethyl- hepta-1,5-diene (isomer) 1101 [n.f.] D-C-P 2-Methyl-butanal 850 [915] D-C-P Cis-hex-3-enal 1113 [1072-1137] D-C-P Dichloromethane 859 [n.f.] PA CDVB Heptan-2-one 1123 [1170-1181] PA CDVB D-C-P Ethanol 883 [900-929] PA D-C-P Heptanal 1126 [1174-1186] PA CDVB D-C-P 1-Methoxy-hexane 889 [941] D-C-P o-Xilene 1128 [1174-1191] D-C-P 4-Hydroxy-butan-2- one 892 [n.f.] PA Limonene 1139 [1178-1206] PA D-C-P Pentanal 896 [935-1002] PA 3-Methyl-butan- 1-ol 1141 [1205-1211] D-C-P 3-Ethyl-octa-1,5-diene (isomer) 907 [n.f.] D-C-P 2-Methyl-butan- 1-ol 1142 [1208-1211] PA PDMS CDVB D-C-P 3-Methyl-butanal 912 [910-937] D-C-P 2,2-Dimethyl- oct-3-ene 1144 [n.f.] D-C-P Propan-2-ol 918 [n.f.] PA CDVB D-C-P E-Hex-2-enal 1160 [1207-1220] PA CDVB D-C-P 3-Ethyl-octa-1,5-diene (isomer) 930 [1018] PA D-C-P Dodecene 1164 [n.f.] PA D-C-P Pent-1-en-3-one (isomer) 932 [973-1016] D-C-P Ethyl hexanoate 1170 [1223-1224] PA CDVB D-C-P Olive Oil Composition: Volatile Compounds 31 Compound name LRI Experimental [Literature] SPME Fibres Compound name LRI Experimental [Literature] SPME Fibres Ethyl butanoate 946 [1023] PA D-C-P Pentan-1-ol 1184 [1250-1255] PA CDVB D-C-P Toluene 952 [1030-1042] D-C-P  -Ocimene 1186 [1242-1250] CDVB D-C-P Ethyl 2-methyl- butanoate 963 [n.f.] D-C-P Tridec-6-ene (isomer) 1187 [n.f.] D-C-P Deca-3,7-diene (isomer) 985 [1077] D-C-P Styrene 1199 [1265] PA CDVB D-C-P Deca-3,7-diene (isomer) 994 [1079] D-C-P Hexyl acetate 1209 [1274-1307] PA CDVB D-C-P Hexanal 1000 [1024-1084] PA CDVB D-C-P 1,2,4- Trimethylbenzene 1223 [1274] PA PDMS CDVB D-C-P 3-Methylbutyl-acetate 1037 [1110-1120] D-C-P Octanal 1231 [1278-1288] PA PDMS CDVB D-C-P 2-Methyl-propan-1-ol 1054 [1089] PA E-4,8-Dimethyl- nona-1,3,7-triene 1247 [1306] PA PDMS CDVB D-C-P Ethylbenzene 1056 [1119] PA CDVB D-C-P E-Pent-2-en-1-ol 1250 [n.f.] D-C-P Z-Hex-3-enyl acetate 1258 [1300-1338] PA CDVB D-C-P Hepta-2,4-dienal (isomer) 1453 [1463-1487] PA CDVB D-C-P E-Hept-2-enal 1272 [1320] CDVB D-C-P Decanal 1456 [1484-1485] PA CDVB Z-Pent-2-en-1-ol 1281 [1320] PA D-C-P  -Humulene 1472 [n.f.] PA 6-Methyl-hept-5-en-2- one (isomer) 1285 [1335-1337] PA CDVB D-C-P Benzaldehyde 1488 [1513] PA CDVB D-C-P Hexan-1-ol 1290 [1316-1360] PA CDVB D-C-P  -Terpineol 1493 [1694] D-C-P 4-Hidroxy-4-methyl- pentan-2-one 1313 [n.f.] D-C-P E-Non-2-enal 1494 [1502-1540] PA D-C-P Olive Oil – Constituents, Quality, Health Properties and Bioconversions 32 Compound name LRI Experimental [Literature] SPME Fibres Compound name LRI Experimental [Literature] SPME Fibres E-Hex-3-en-1-ol 1320 [1356-1366] PA CDVB D-C-P Propanoic acid 1495 [1527] D-C-P Z-Hex-3-en-1-ol 1322 [1351-1385] PA D-C-P Octan-1-ol 1504 [1519-1559] PA CDVB D-C-P 4-Methyl-pent-1-en-3- ol 1330 [n.f.] PA D-C-P 2-Diethoxy- ethanol 1565 [n.f.] PA D-C-P Methyl Octanoate 1331 [1386] D-C-P E,E-Nona-2,4- dienal 1574 [n.f.] PA Nonan-2-one 1340 [1382] PA D-C-P Methyl benzoate 1587 [n.f.] D-C-P Nonanal 1344 [1382-1396] PA CDVB D-C-P Butanoic acid 1588 [1634] PA D-C-P E-Hex-2-en-1-ol 1348 [1368-1408] CDVB D-C-P 4- Hydroxybutanoi c acid 1593 [n.f.] D-C-P Z-2-Hex-2-en-1-ol 1348 [1410-1417] PA D-C-P E-Dec-2-enal 1606 [1590] PA CDVB D-C-P Oct-3-en-2-one (isomer) 1349 [1455] D-C-P Acetophenone 1617 [1624] D-C-P Hexa-2,4-dienal (E,E), (E,Z) or (Z,Z) 1349 [1397-1402] D-C-P 2-Methyl- butanoic acid 1621 [1675] D-C-P Ethyl octanoate 1353 [1428] D-C-P Nonan-1-ol 1628 [1658] PA CDVB D-C-P Hexa-2,4-dienal (isomer) 1360 [1397-1402] D-C-P  -Muurolene 1680 [n.f.] D-C-P E-Oct-2-enal 1367 [1425] PA D-C-P Aromadendrene 1681 [n.f.] PA PDMS CDVB D-C-P 1-Ethenyl-3-ethyl- benzene 1378 [n.f.] D-C-P 1,2-Dimethoxy- benzene 1686 [n.f.] PA PDMS D-C-P Oct-1-en-3-ol (isomer) 1392 [1394-1450] PA CDVB D-C-P 4-Methyl- benzaldehyde 1690 [n.f.] D-C-P Heptan-1-ol 1400 [n.f.] PA CDVB D-C-P Pentanoic acid 1700 [1746] PA CDVB C-C-P Olive Oil Composition: Volatile Compounds 33 Compound name LRI Experimental [Literature] SPME Fibres Compound name LRI Experimental [Literature] SPME Fibres Linalool 1403 [1550] CDVB Butyl heptanoate 1717 [n.f.] D-C-P Acetic acid 1408 [1434-1450] CDVB D-C-P E-Undec-2-enal 1726 [n.f.] PA CDVB D-C-P Hepta-2,4-dienal (isomer) 1421 [1488-1519] D-C-P Methyl salycilate 1758 [1762] D-C-P 2-Ethyl-hexan-1-ol 1436 [1491] PA CDVB D-C-P E, E-Deca-2,4- dienal 1780 [1710] PA CDVB D-C-P  -Copaene 1440 [1481-1519] PA CDVB D-C-P 2-Methoxy- phenol (guaicol) 1836 [1855] PA CDVB D-C-P  -Cubebene 1442 [n.f.] D-C-P 2-Methyl- naphthalene 1839 [n.f.] D-C-P Benzyl alcohol 1846 [1822-1883] PA CDVB D-C-P Octanoic acid 2047 [2069] PA D-C-P Phenylethyl alcohol 1890 [1859-1919] PA CDVB D-C-P Nonanoic acid 2198 [n.f.] PA CDVB D-C-P Heptanoic acid 1900 [1962] PA D-C-P 4-Ethyl-phenol 2212 [n.f.] D-C-P n.d. denote not determined; n.f. denote not found; LRI denote linear retention indices for DB-Wax column. LRI between brackets represents the data range found in literature: Angerosa, 2002; Contini & Esti 2006; Flath et al., 1973; Kanavouras et al., 2005; Ledauphin et al,. 2004; Morales et al., 1994; Morales et al., 1995; Morales et al., 2005; Reiners & Grosch, 1998; Tabanca et al., 2006; Vichi et al., 2003a., 2003b; Vichi et al., 2005; Zunin et al., 2004. Table 1. Compounds identified in olive oil samples of Galega Vulgar by means of HS-SPME- GC/TOFMS. The fibres used are polydimethylsiloxane (PDMS), polyacrylate (PA), carbowax/divinylbenzene (CDVB), and divinylbenzene/carboxene/polidimethylsiloxane (D-C-P). The extraction and analysis procedure for all fibres was: 15 g of olive oil sample in 22 mL vial immersed into a water bath at 38 ºC. Extraction time was 30 min. Fibre desorption time was 300 seconds into an injection port heated at 260 ºC. Splitless time of 1 min. A GC System 6890N Series from Agilent coupled to a Time of Flight (TOF) mass detector GCT from Micromass using the acquisition software MassLynx 3.5, MassLynx 4.0 and ChromaLynx The system was equipped with a 60 m × 0.32 mm i.d. with 0,5 m d f DB- Wax column or a 30 m × 0.32 mm i.d. with 1 m d f DB-5 column, both purchased from J&W Scientific (Folsom USA). Acquisition was carried out using a mass range of 40-400 u.; transfer line temperature was set at 230 ºC; ion source 250 ºC. Helium was used as carrier at 100 kPa; Oven temperature was programmed from 50 ºC for three minutes and a temperature increase of 2 ºC/min up to 210 ºC hold for 15 minutes and a rate of 10 ºC/min up to 215 ºC and hold. [...]... Health Properties and Bioconversions Quality parameters Calibration range Spectroscopic range (nm) Number of PLS regressors R² Oleic acidity (% oleic acid) 0. 12 - 1.555 780 - 25 00 3 0.8407 Peroxide value (meq O / kg oil) 3.76 - 13.98 1000 – 23 33 2 0.9 628 K2 32 0. 922 - 1.548 1333 – 22 22 3 0.99 42 K270 0.0 62 - 0.1178 1333 – 22 22 3 0.9 825 ΔK -0.004 - 0.01 1333 - 22 22 2 0.4344 Table 1 Prediction of quality. .. 23 00 1 0.9 822 Arachiric 0.3 82 - 0.6 42 1000 - 22 22 1 0.9896 Eicosenoic 0 .21 2 - 0.431 1000 - 23 00 2 0.9 821 Behenic 0.0 42 - 0.411 300 - 23 00 2 0.88 92 Heptadecenoic 0.053 - 0.356 300 - 23 00 2 0.8081 Heptadecanoic 0. 025 - 0 .29 1000 - 23 00 2 0.8337 Lignoceric 0. 026 - 0 .20 5 1333 - 22 22 1 0.85 32 Table 2 Prediction of fatty acids of the Sicilian extra virgin olive oils of Figure 9 6 Diffuse-light absorption... olive oil collection of Figure 9 Fatty acids Calibration range (%) Spectroscopic range (nm) # PLS regressors R² Oleic 65.847 - 76.334 1333 - 22 22 1 0.9986 Palmitic 9. 62 - 17.113 300 - 23 00 2 0.9847 Linoleic 4.469 - 10.95 1333 - 22 22 1 0.9553 Stearic 2. 565 - 4.046 780 - 25 00 2 0.99 42 Palmiticoleic 0.367 - 1.457 1333 - 22 22 2 0.9504 Linolenic 0.646 - 1.066 1000 - 23 00 1 0.9 822 Arachiric 0.3 82 - 0.6 42. .. 79 (20 %); 91(100%); 21 (96%); 137 (17%); 1 52( 6%) M+ 1350 [n.f.] 41( 42% ); 55 (29 %); 57 (25 %); 67(100%); 82( 51%) 41(11%); 42( 10%); 43( 82% ); 55(4%); 57(6%); 58(100%); 59 (24 %); 60 (6%); 71 (24 %); 85 (2% ); 98(4%); 113 (2% ); 127 (2% ); 156 (2% ) M+ 43(100%); 56(39%); 61(33%); 70 (24 %); 83(16%); 98(19%); 126 (10%) 41(64%); 43(55%); 55(100%); 56(98%); 69(71%); 70(94%); 83(57%); 98(34%); 110(5%); 136 (2% ) 43(39%); 65 (22 %);... Vol 46, pp 648-653 38 Olive Oil – Constituents, Quality, Health Properties and Bioconversions Angerosa F.; Mostallino, R.; Basti, C & Vito, R (20 00) Virgin Olive Oil Odor Notes: Their Relationships With Volatile Compounds From the Lipoxygenase Pathway and Secoiridoid Compounds Food Chemistry Vol 68, pp 28 3 -28 7 Angerosa, F (20 02) Influence of volatile compounds on virgin olive oil quality evaluated by... acids; in particular, the 23 027 0 nm band shows high absorption when conjugated dienes and trienes of unsaturated fatty acids are present For this reason, the absorbances measured at 23 2 nm and 27 0 nm, namely K2 32 and K270, provide an official method for olive oil quality control, which is capable of detecting product oxidation and adulteration by means of rectified oils In addition, the 300-400 nm band provides... t -3 -1 -1 5 DF 2 DF 3 -0.18 -0 .2 -0.04 -0.06 -0.08 -0 .22 0.16 0.18 0 .2 0 .22 DF 1 0 .24 -0.1 -0. 12 -0.14 DF 2 -2 -2 5 -3 -3 5 -4 TUS CA NY S ICILY S P A IN 1 2 3 DF 1 4 5 x 10 -3 Fig 8 Effectiveness of scattered colorimetry for discriminating the geographic area of production: Italian extra virgin olive oils from different regions and oils from retailers (left); Spanish and Italian oils (right) (with... 0.8 0.8 O1 O2 O3 O4 0.7 0.6 0.5 Absorbance Absorbance 0.6 0.4 0.3 0.5 0.4 0.3 0 .2 0 .2 0.1 0.1 0 600 800 1000 120 0 1400 Wavelength ( nm ) 0 1600 1.5 05 05 05 25 25 25 50 50 50 75 0.5 0 F1 75 95 75 -0.5 1000 120 0 1400 Wavelength ( nm ) 1600 0.6 25 95 0.4 50 F2 F5 -2 95 F4 F2 -0.4 F5 0 2 PC 1 ( 89.8 % ) F5 F1 -0 .2 F4 F2 0 .2 0 75 F1 95 -1.5 -4 800 0.8 DF 2 1 -1 600 1 05 PC 2 ( 7.4 % ) F1 F2 F4 F5 0.7 4... García-González, D L (20 07) Volatile compounds characterizing Tunisian Chemlali and Chétoui virgin olive oils Journal of Agricultural and Food Chemistry, 55, 78 52- 7858 46 Olive Oil – Constituents, Quality, Health Properties and Bioconversions Tovar, M.J.; Romero, M.P.; Girona, J & Motilva, M.J (20 02) L-phenylalanine ammonia-lyase activity and concentration of phenolics in developing olive (Olea europaea... et al., 20 00), to predict acidity and peroxide index (Armenta et al., 20 07), and to detect and quantify the adulteration with sunflower and corn oil (Özdemir et al., 20 07) and other vegetable oils (Christy et al., 20 04; Öztürk et al., 20 10) Greek oils from Crete, Peloponnese and Central Greece were classified both by the UV-VIS (Kružlicová et al., 20 08) and the VIS-NIR bands (Downey et al., 20 03), the . Aceites Vol 29 , pp. 21 1 -21 8 Olive Oil – Constituents, Quality, Health Properties and Bioconversions 42 Kalua, C. M.; Allen, M. S.; Bedgood Jr, D. R., Bishop, A. G. & Prenzler, P. D. (20 05) 1350 [n.f.] 41( 42% ); 55 (29 %); 57 (25 %); 67(100%); 82 ( 51% ) PDMS D-C-P Decan -2- one 1 428 [n.f.] 41(11%); 42( 10%); 43( 82% ); 55(4%); 57(6%); 58(100%); 59 (24 %); 60 (6%); 71 (24 %); 85 (2% ); 98(4%); 113 (2% );. Olive Oil – Constituents, Quality, Health Properties and Bioconversions 24 In a recent study, concerning the behaviour of super-intensive Spanish and Greek olive cultivars